Origin of the Monsoon:

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  • Classcial Theories:
  1. Halley’s Thermal concept: Indian monsoon is because of contrast between Indian Subcontinent and adjoining Indian Ocean. Halley’s theory, suggested in 1686, considers the summer monsoon to be a regional phenomenon.
  2. Aerological concept: This was suggested by R. Scherhag in 1948. According to this theory, monsoon circulation develops due to changes in air temperature at all levels over the Indian Subcontinent and adjoining Indian Ocean.

 

  • Modern theories:
  1. Dynamic Theory: Flohn (1951) according to Flohn, the monsoon is a global phenomenon due to global shift in pressure belts. The shift in pressure belts bring the ITC much more into the northern margin is around 30 degrees north over the Indian subcontinent. This brings the SE trades over the Indian subcontinent as south westerly monsoons. Similarly, the shift in pressure belts globally when it is winter for the N. Hemisphere pushes the ITC to a little more south of the equator. This brings the sub- tropical high on to the southern slopes of Himalayas and hence the NE trades blow from northeast to southwest as northeast monsoons.

 

  1. Tibet and Easterly Jet: P. Koteshwaram and Flohn concluded that heating of Tibet in summer strengthens the monsoonal circulation with an Average height of 4Kms above the MSL, Tibetan surface is warmed in summer and generates ascending warm air. The air turns to its right and sinks over the Arabian sea and joins the southwesterly winds there by strengthening the monsoon. This circulation is part of the tropical easterly jet stream.

 

  1. Role of Sub- Tropical westerly Jet: The sub-tropical westerly jet normally located on the south slopes of Himalayas and the northeast plains disintegrates in summer due to intense heating of the northern plains and the global shift in pressure belts to the north in summer of the northern hemisphere. This facilities the onset of the monsoon over india by facilitating the development of the monsoon trough.

 

  1. The Somali Jet: The offshore areas of Somalia develop clod waters due to upwelling giving birth to the Somali current. The cold waters led to low temperature along Somali coast ( 15 degrees centigrade) whereas along Mumbai, the temperature is 30 degrees cent centigrade. This thermal gradient leads to development of the Somali jet stream blowing from western Arabian sea to the eastern Arabian sea. This adds moisture bearing winds to the southwest monsoon.

 

  1. The Monsoon trough: This is the ITC which forms as a huge gash of low pressure from the desert of Arabian to Bay of Bengal. This covers the northern plains and induces the SE trades to cross the equator and give birth the south westerly winds.

 

  1. El Nino: The development of El Nino conditions influence the monsoon. During El Nino, the southern oscillation (i.e., the differences in pressure between port  Darwin and Tahiti, French Polynesia). If the southern oscillation is negative, Darwin pressure is higher than Tahiti due to high pressure over Australia, western pacific and adjacent Indian ocean. The high pressure conditions also cover the Indian ocean and the landmass of peninsular India. This prevents the movement of southeast trades towards the landmass of India. If the southern oscillation is positive, Tahiti pressure is more than that of Darwin. Low pressure is over North Australia and over adjacent Indian Ocean. This induces northward movement of southeast trades and hence strengthens monsoonal circulation. The combination of El Nino current (which appears as a warm saline current along the west coast of S. America replacing the cold Humboldt Current during a negative El Nino) and the southern oscillation is caused ENSO.

 

Onset of Monsoon

The summer monsoon over the Indian subcontinent first arrives over Kerala situated at the southern tip of the Indian Peninsula around 1st June with a standard deviation of about 7 days. The arrival of the monsoon over the region is noticed by wide spread persistent and heavy rainfall replacing the occasional pre-monsoon rains.

 

Retreat Of Monsoon

This  lasts between September and end of December. This is the season of retreating monsoons. The monsoon trough over the northern plains weakens and begins to shift southward. The retreating monsoon brings rain to coastal Tamil Nadu, Krishna- Godavari delta, region west of Aravallis and to northeast India. The retreat of the monsoon begins on 1st September (i.e., in Rajasthan), 15th September in Punjab- Haryana plains, 10th October from Ganges plains, 1st December from Tamil Nadu and by 15th December, the southwest monsoon withdraws from india completely. The retreating monsoon brings rainfall to AP south of Krishna delta and Tamil Nadu. The rainfall in Tamil Nadu in October/November, is 38.25 cms which is about 39% of its annual rainfall while for coastal Tamil Nadu it is 50% of the annual.

This is the season for tropical Cyclones-2/”>Cyclones that affect the Indian landmass. Cyclones that affect the east coast and the west coast from in the southern portions of the Bay of Bengal, particularly during the retreating monsoon season. Maximum number of that form in the Bay of Bengal form in November. More number of cyclones form in the bay of Bengal than the Arabian sea.

 

 

 

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The monsoon is a seasonal prevailing wind that blows from the southwest in the summer and from the northeast in the winter. It is caused by the difference in temperature between the land and the ocean. During the summer, the land heats up faster than the ocean. This causes the air above the land to rise, and the air above the ocean to sink. This creates a pressure difference between the land and the ocean, which drives the wind from the ocean to the land. This wind is what brings the rain to the land during the summer.

In the winter, the land cools down faster than the ocean. This causes the air above the land to sink, and the air above the ocean to rise. This creates a pressure difference between the land and the ocean, which drives the wind from the land to the ocean. This wind is what brings the dry weather to the land during the winter.

The monsoons are a vital part of the Climate in many parts of the world. They provide much-needed rain for agriculture and other human activities. They also play an important role in the water cycle and the global climate.

The difference in temperature between the land and the ocean is caused by the different heat capacities of land and water. Land has a lower heat capacity than water, which means that it heats up and cools down more quickly. This difference in temperature causes the air above the land to rise and the air above the ocean to sink. This creates a pressure difference between the land and the ocean, which drives the wind from the ocean to the land.

The pressure difference between the land and the ocean is caused by the difference in temperature between the land and the ocean. The warmer air above the land rises, while the cooler air above the ocean sinks. This creates a pressure difference between the land and the ocean, which drives the wind from the ocean to the land.

The wind that blows from the ocean to the land during the summer is called the southwest monsoon. The southwest monsoon is a warm, moist wind that brings rain to the land. The wind that blows from the land to the ocean during the winter is called the northeast monsoon. The northeast monsoon is a dry, cool wind that brings dry weather to the land.

The rain that falls during the summer is caused by the southwest monsoon. The southwest monsoon brings warm, moist air from the ocean to the land. This warm, moist air rises and cools, causing the water vapor in the air to condense and form clouds. The clouds release the water as rain, which falls on the land.

The dry weather that occurs during the winter is caused by the northeast monsoon. The northeast monsoon brings dry, cool air from the land to the ocean. This dry, cool air sinks and prevents the formation of clouds. As a result, there is little or no rain during the winter.

The importance of the monsoons to agriculture and other human activities is significant. The monsoons provide much-needed rain for agriculture. Without the monsoons, many parts of the world would be too dry to support agriculture. The monsoons also play an important role in other human activities, such as transportation and tourism.

The role of the monsoons in the water cycle and the global climate is also significant. The monsoons help to distribute water around the globe. They also help to regulate the Earth’s temperature. Without the monsoons, the Earth’s climate would be much more extreme.

In conclusion, the monsoons are a vital part of the climate in many parts of the world. They provide much-needed rain for agriculture and other human activities. They also play an important role in the water cycle and the global climate.

What is the monsoon?

The monsoon is a seasonal wind pattern that occurs in many parts of the world, including Asia, Africa, Australia, and the Americas. It is characterized by a reversal of wind direction between the summer and winter months. In the summer, the monsoon blows from the ocean to the land, bringing with it moisture and rain. In the winter, the monsoon blows from the land to the ocean, bringing with it dry air.

What causes the monsoon?

The monsoon is caused by the difference in temperature between the land and the ocean. During the summer, the land heats up faster than the ocean. This causes the air above the land to rise, creating an area of low pressure. The air above the ocean is cooler and denser, so it flows towards the land to fill the low pressure area. This flow of air is the monsoon.

What are the effects of the monsoon?

The monsoon has a significant impact on the climate of many parts of the world. It brings much-needed rain to many areas that would otherwise be dry. The monsoon also helps to regulate the temperature of the land and the ocean.

What are some of the challenges associated with the monsoon?

The monsoon can also cause problems, such as flooding, landslides, and drought. Flooding can occur when the monsoon rains are too heavy. Landslides can occur when the monsoon rains cause the ground to become saturated. Drought can occur when the monsoon rains are too Light.

How can we mitigate the challenges associated with the monsoon?

There are a number of things that can be done to mitigate the challenges associated with the monsoon. These include:

  • Building Dams and reservoirs to store water during the monsoon season.
  • Planting trees to help prevent Soil erosion.
  • Raising awareness of the risks associated with the monsoon.
  • Developing early warning systems to help people prepare for the monsoon.

What is the future of the monsoon?

The monsoon is likely to become more intense in the future due to Climate Change. This could lead to more flooding, landslides, and drought. It is important to take steps to mitigate the challenges associated with the monsoon in order to protect people and property.

The monsoon is a seasonal reversal of wind direction between the land and the ocean, particularly in the tropics. It is caused by the difference in temperature between the land and the ocean. In the summer, the land heats up faster than the ocean, causing the air above the land to rise. This creates an area of low pressure over the land. The air from the ocean, which is cooler and denser, flows in to fill this low pressure area. This is the monsoon wind.

The monsoon is a major factor in the climate of many parts of the world, including India, Southeast Asia, and Australia. It brings much-needed rain to these regions, which are otherwise dry for much of the year. The monsoon also plays a role in the distribution of rainfall in other parts of the world, such as North America and Europe.

The monsoon is a complex phenomenon that is not fully understood. However, scientists believe that it is caused by a combination of factors, including the Earth’s rotation, the tilt of the Earth’s axis, and the difference in temperature between the land and the ocean.

Here are some MCQs about the monsoon:

  1. The monsoon is a seasonal reversal of wind direction between the land and the ocean. True or False?
  2. The monsoon is caused by the difference in temperature between the land and the ocean. True or False?
  3. The monsoon is a major factor in the climate of many parts of the world. True or False?
  4. The monsoon is a complex phenomenon that is not fully understood. True or False?
  5. Scientists believe that the monsoon is caused by a combination of factors, including the Earth’s rotation, the tilt of the Earth’s axis, and the difference in temperature between the land and the ocean. True or False?

Answers:
1. True
2. True
3. True
4. True
5. True

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